Adequate use of storage in the power system can enable the integration of large amounts of electricity generated from intermittent renewable sources, reduce system operating costs and ultimately affect electricity prices. In addition to the possibility of storing energy for later use, there are many other services that make energy storage useful in market-oriented power systems, such as frequency regulation, voltage regulation, provision of rotating and non-rotating reserves, peak load smoothing, black start, etc. Each purpose has specific requirements for response time, amount of energy needed, etc. and all energy storage technologies, which differ significantly in their characteristics, are not suitable for all purposes. Therefore, existing and some new energy storage technologies are being intensively researched and improved. A large increase in energy storage capacities is expected.

Optimal energy storage requirements depend on the characteristics of the power system (mostly on the properties of individual types of power plants and the share and characteristics of renewable sources), on the movement of electricity prices and ancillary services on energy exchanges, the capabilities of energy storage, etc.